Mechanism of Hormone Action — Prelims Strategy
Prelims Strategy
To excel in NEET questions on the 'Mechanism of Hormone Action,' a multi-pronged strategy is essential. Firstly, master the classification: clearly differentiate between water-soluble (peptide, protein, catecholamine) and lipid-soluble (steroid, thyroid) hormones.
For each class, memorize the typical receptor location (cell surface vs. intracellular) and the general outcome (rapid, transient changes vs. slower, long-lasting gene expression). Secondly, understand the specific pathways in detail.
For water-soluble hormones, focus on the cAMP pathway (G-protein, adenylyl cyclase, cAMP, PKA) and the IP3/DAG pathway (G-protein, phospholipase C, PIP2, IP3, DAG, Ca, PKC). Be able to trace the signal from hormone binding to the final cellular response.
For lipid-soluble hormones, understand the sequence: diffusion, intracellular receptor binding, hormone-receptor complex formation, nuclear translocation, HRE binding, and gene transcription/translation.
Thirdly, pay close attention to keywords and specific molecules. Questions often hinge on identifying the correct second messenger, the enzyme involved (e.g., adenylyl cyclase, phospholipase C), or the DNA binding site (HRE).
Fourthly, practice sequencing questions; these are common and require a clear understanding of the chronological order of events. Finally, avoid common traps such as confusing ATP with cAMP (ATP is a substrate, cAMP is the messenger) or assuming all hormones enter the cell.
Use flowcharts and diagrams for revision to visually reinforce the pathways.